Material and methods: This study represent a prospective randomized open label controlled trial. The study will take place in the intensive care unit of the University Hospital of Larissa. Consecutive sampling will be used to recruit patients hospitalized in the ICU department between October of 2009 and October of 2010. The patients who undergo radiographic studies with the administration of contrast agent will be randomly assigned to receive IV either 1200mg acetylcysteine and 2g ascorbic acid or placebo at least 2 hours before the start of the index procedure, followed by 1200mg acetylcysteine and 1,5g ascorbic acid or placebo the night and the morning after the examination. All the patients independently from the randomization will receive hydration with at least 100ml/h IV 0,9% or 0,45% sodium chloride in water, from randomization until at least 6 hours after the examination. The variation of the hydration type and rate allowed for adjustment according the special needs of every patient.